Developers for photographic reversal processes



United States Patent O 3,021,212 DEVELOPERS FOR PHOTOGRAPH-HG REVERSAL PROCESSES Nancy H. King, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Aug. 14-, 1959, Ser. No. 833,685 20 Ciaims. (Cl. 9629) The present invention relates to improved developers for producing direct positive images, and more particularly relates to a method of utilizing such developers to produce direct positive images by a reversal technique utilizing only one treating bath in order to obtain reversal.

Frequently, reversal development is an involved process and involves no fewer than five essential operations: development of the latent image, bleaching and clearing to remove the developed negative silver image, exposing the remaining silver halide to light, and finally, reducing the silver halide to metallic silver in order to form the reversal image. In addition, there are likely to be several other operaL'ons including rinsing, hardening, fixing and washing treatments.

On the other hand, many of the previously-described processes for producing direct positive images in a onebath reversal process by means of chemical substances result in too high a minimum density to make the use of such chemical treatment practical.

Reversal by chemical substances, such as hydrogen peroxide, sodium arsenite, sodium hypophosphite, stannous chloride, persulfates, organic peroxides and the like have previously been described. See article by Walter Clark in The Photographic Journal, vol. 64 (1954), pages 363-3 69.

According to the present invention, photographic developing baths are provided which produce a direct positive image without necessitating elaborate processing techniques and without the necessity for multiple treatments in rinsing baths, fixing baths, etc.

It is, therefore, an object of my invention to provide new photographic developers for obtaining in a single step positive black-and-white images. Another object is to provide a method for using such photographic developing baths. Still another object is to provide photographic developing baths which produce positive images in a one-bath reversal process. Other objects will become apparent from a consideration of the following description and examples.

According to the present invention, new photographic developing solutions are provided which contain an alkali metal selenocyanide. These salts can be represented by the following general formula:

MSeCN wherein M represents an alkali metal, such as sodium, potassium, etc.

The following examples will serve to illustrate briefly the new photographic developers useful in practicing my invention, and methods for using such developers.

Example 1 Ordinary X-ray film comprising a photographic silver bromiodide emulsion coated on cellulose acetate support was exposed in the normal manner to light of the type minutes at 68 F. in a solution having the following composition:

p N-methylaminophenol sulfate "grams" 2.5 Sodium sulfite (desiccated) do 30.0 Hydroquinone do 2.5 Sodium metaborate octahydrate do 10.0 Potassium bromide do 0.5 Carbitol ccs 100.0 Borax grams 10.0 Potassium selenocyanide do 2.0

Water to make 1 liter.

A medium-to-fine grain positive silver bromiodide emulsion of low gelatin content was exposed in the normal manner and then processed for 5 to 20 seconds at 95 F. in a solution having the following composition:

Grams Phenidone developer 10.0 Sodium isoascorbat 40.0 Sodium selenocyanide 20.0 Sodium hydroxide 30.0

Water to make 1 liter.

'1 1-pheny1-3-pyrazolidone.

A reversed image was obtained which was reddish in tone and it was found unnecessary to fix the image in the normal manner (fixation showed no loss of density in any area after fixation). It was also found that the reversal effect was obtained either in total darkness or by development underrsafelight conditions suitable for the product being processed.

Example 3 A fine-grain, slow, cine-positive photographic gelatinosilver-bromiodide emulsion was coated on a conventional cellulose acetate support and exposed in the normal manner. This film was then developed for 20 seconds at 95 F. in a solution having the following composition:

I Grams Phenidone developer 10.0 Sodium isoascorbate 40.0 Potassium selenocyanide 40.0 Sodium hydroxide 30.0

Water to make 1 liter.

A reddish reversal image was obtained.

The phenidone developer in the above developing composition can be replaced by an equivalent amount of Elon-developer, although somewhat increased silvering of the emulsion is produced by this change.

given by intensifying screens and then developed for 10 Example 4 Another sample of the silver bromiodide emulsion described in Example 3 was processed in the developer shown in that example, except that 4 cos. of monothioglycerol were added to the developer. Addition of this material caused an increase in the maximum density with no apparent change in the image tone.

Example 5 A fine-grain, slow, cine-positive photographic gelatinosilver-brorniodide emulsion was coated on a conventional cellulose acetate support and exposed in the normal manner. The exposed film was then'develop'ed for 20 seconds at 95 F. in a solution having the following composition:

Phenidone developer .grarns 10.0 Sodium isoascorbate do 40.0 Sodium hydroxide do 30.0 Potassium selenocyanide do 40.0 5,;8-Dithiasuberic acid do 40.0 Monothioglycerol ml 5.0

Water to make 1.0 liter.

A reversed image having a black or blue-black tone was produced.

Omission of the monothioglycerol from the developing composition of Example 5 caused a marked decrease in the reversal effect as a result of the presence of the dithiasuberic acid. However, addition of the monothioglycerol provided a convenient means of controlling the reversal of the selenocyanide, and overcoming the undesired effects at the dithiasuberic acid.

The alkali metal selenocyanides used in my invention have a rather marked solvent effect on the silver halides and thus make it possible to use the developers of my invention to obtain direct positive images by the dilfusion transfer process. The following example will serve to illustrate this technique as applied to my new photographic developers.

Example 6 A photographic film comprising a silver bromiodide negative emulsion coated on a cellulose acetate support was exposed in the normal manner and bathed for 6 seconds at room temperature in a solution having the following composition:

Grams Hydroquinone 35 Sodium sulfit i 80 Sodium .selenocyanide 28;

Sodium hydroxide Water to make 1.0 liter.

Immediately after bathing the'film was rolled in intimate contact with a paper receiving sheet nucleated with lead sulfide. After contact for 2 minutes, the film was stripped from the receiving sheet, leaving a positive image having high maximum density and adequate scale on the receiving sheet. The results were equivalent to those produced with the same materials and a similar developer containing about 15 grams/liter of sodium thiosulfate instead of sodium selenocyanide. Use of lower concentrations of sodium selenocyanide caused commensurate loss in the density of the positive images, although this was compensated for by using silver bromiodide negatives of higher speed.

The exact mechanism leading to the formation of direct positive images by application of the novel photographic developers of my invention is not completely understood. However, it is believed that the order of events is somewhat similar to that of a monobath in the areas which have received the highest exposures developed in a normal manner. For this reason, it may be desirable to slightly underexpose the original light-sensitive material. The unexposed areas or areas of very low exposure are seen to become transparent, and at this point the similarity to mcnobaths no longer holds. Further processing causes a gradual reduction in the transparency of the cleared areas until these areas transmit substantially less light than the exposed areas. The difference in density between the unexposed areas and the exposed areas may be as much as 6.0 or more.

The effect of the alkali metal selenocyanide in photographic developers has been observed to occur in a variety of developers designed for use in black-and-white photography. These developers can comprise conventional blackand-White developers 7 including polyhydroxybenzenes (e.g., hydroquinone, chlorohydroquinone, alkylsubstituted hydroquinones, etc.), p-aminophenols, B-pyrazolidone, etc. S-pyrazolidones useful in the photographic developers of my invention include those described in Kendall US. Patent 2,289,367, issued July 14, 1942; Reynolds et al. US. Patent 2,743,279, issued April 24, 1956, and Allen et al. U.S. Patent 2,772,282, issued November 27, 1956, for example. Typical 3-pyrazolidone described by the patents include:

1-phenyl-3 -pyrazolidone 1-m-nitrophenyl-3-pyrazolidone 1-p-nitrophenyl-3 -pyrazolidone l-p-chlorophenyl-3 -pyrazolidone 1-p-cyanophenyl-3 -pyrazolidone l-p-fl-methanesulfonamidoethylphenyl-3-pyrazolidone 1p-B-hydroxyethylphenyl-Ii-pyrazolidone 1- p-carboxymethylphenyl) -3 -pyrazolidone 1-p-tolyl-3 -pyrazolidone l-o-tolyl-3-pyrazolidone l-m-tolyl-3-pyrazolidone 1- 2-b enzothiazolyl) -3-pyrazolidone 1-phenyl-4,4-dimethyl-3-pyrazolidone 1-p-aminophenyl-4-methyl-4-propyl-3 -pyrazolidone l-p-chlorophenyl-4-methy1-4-ethyl-3-pyrazolidone 1-p-acetamidophenyl-4,4-diethyl-3 -pyrazolidone l-p-B-hydroxyethylphenyl-4,4-dimethyl-B-pyrazolidone l-p-hydroxyphenyl-4,4-dimethyl-3 -pyrazolid one 1-p-methoxyphenyl-4,4-diethyl-3-pyrazolidone 1-p-tolyl-4,4-dimethyl-3-pyrazolidone '1- (7 -hydroxy-2-naphthyl) -4-methyl-4-n-propyl'3- pyrazolidone 1-p-nitrophenyl-4,4-dimethyl-3 -pyrazolidone 1-p-cyanophenyl-4,4-dimethyl-3-pyrazolidone 1-p acetylaminophenyl-4,4-dimethyl-3-pyrazolidone 1-p-benzylphenyl-4,4-dimethyl-3-pyrazolidone 1-methyl-4,4-dimethyl-3-pyrazolidone 1-p-carboxyphenyl-4,4-dimethyl-3 -pyrazolidone 1-carboxymethyl-4,4-dimethyl-3pyrazolidone 1-hydroxyethyl-4,4-dimethyl-3-pyrazolidone l-m-aminophenyl-4,4-dimethyl-3 -pyrazolidone 1-m-chlorophenyl-4-methyl-4-ethyl- 3-pyrazolidone 1-m-acetamidophenyl-4,4-diethyl- 3 -pyrazoli done The concentration of the alkali metal selenocyanide useful in my invention can be varied, depending upon the particular silver halide emulsion being processed, the concentration of silver halide in the emulsion, the pH of the developer, the nature and concentration of the developing agents, the presence or absence of stabilizers, such as sodium sulfite, sodium isoascorbate, etc., and the presonce or absence of toning materials, such as ,B,B'-dithiasuberic acid and monothioglycerol. In general, I have found that quite useful results can be obtained wherein the concentration of the alkali metal selenocyanides vary from about 0.2 to about 50.0 grams per liter of solution.

The activity of the alkali metal selenocyanides useful in my invention can be varied by suitable alteration of the pH of the developing solutions. Particularly useful results have been obtained when the pH of the solution is above about 9.0. Especially useful results have been obtained at a pH of about 9.8 or higher.

Alkaline materials suitable for use in adiusting the pH of the developing solutions are sodium hydroxide,'potasslum hydroxide, sodium carbonate, etc.

The novel developers of my invention can be used to obtain reversed images in treating many of the common photographic gelatino-silver-halide developing-out emulsions. While many of the previous methods of producmg reversal by a chemical means require the use of extremely slow, fine-grain emulsions, it can be seen from the above examples that my invention provides reversed nnages even with high-speed negative bromiodide emulsions. The silver halides of the photographic emulsions useful in practicing my invention can be varied and include not only the silver bromiodide emulsions illustrated in the above examples but emulsions comprising other silver halides, such as silver bromide, silver chlorobromide, silve bromiodide, silver chlorobromiodide, etc.

Development times can vary depending upon the particular emulsion being developed, concentration of ingredients in the developer, etc. The most advantageous time for a given emulsion can be determined by running a series of test strips wherein the only variable in the process is the developing time. Similarly the optimum concentration of ingredients for a given developer can be determined by variation of the concentration of only one of the ingredients in a given series of tests. Such matters are well understood by those skilled in the art.

As indicated above, it is generally unnecessary to stabilize or fix the photographic images produced according to the present invention. However, where it is desirable to fix or stabilize the photographic image, it has been found that this can conveniently be done by merely contacting the processed photographic material with a Web or stabilizing paper having a coating thereon containing the fixing or stabilizing ingredient. For instance, a suitable fixing paper can be made by precipitating sodium thioglyceride from a solution containing one mole of a-monothioglycerol and one mole of sodium hydroxide. A paper base, which may be coated with a colloid layer, such as gelatin, carboxymethyl cellulose, etc., is then soaked for 30 seconds in a solution of a sodium thioglyceride and then air dried. The fixing paper can then be processed in contact with the photographic material with a sufficient amount of liquid between the two surfaces. This liquid can come solely from the developed photographic material and/ or from the wetted fixing paper. Alternatively, the fixing agent can be a different mercapto compound, such as thiobarbituric acid, ora sodium salt thereof.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be eifected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

What I claim as my invention and desire secured by Letters Patent of the United States is:

1. A photographic developer for producing direct positive images comprising an alkaline solution of an organic silver halide developing agent for producing black-andwhite images and from about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide.

2. A photographic developer for producing direct positive images comprising an alkaline solution of a polyhydroxybenzene silver halide developing agent and from about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide.

3. A photographic developer as defined in claim 2 wherein the alkali metal selenocyanide is potassium selenocyanide.

4. A photographic developer as defined in claim 2 wherein the alkali metal selenocyanide is sodium selenocyanide.

5. A photographic developer for producing direct positive images comprising an alkaline solution of a 3-pyrazolidone silver halide developer and fro-m about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide.

6. A photographic developer for producing direct positive images comprising an alkaline solution of a 3-pyrazolidone-silver halide developer, from about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide and a water-soluble ascorbic acid salt.

7. A. photographic developer as defined in claim 5 wherein the alkali metal selenocyanide is potassium selenocyanide.

8. A photographic developer as defined in claim 5 wherein the alkali metal selenocyanide is sodium selenocyanide.

9. A photographic developer for producing direct positive images comprising an alkaline solution of hydroquinone and from about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide.

10. A photographic developer for producing direct posi tive images comprising an alkaline solution of hydroquinone and from about 0.2 to about 50.0 grams per liter of solution of potassium selenocyanide.

11. A photographic developer for producing direct positive images comprising an alkaline solution of hydroquinone and from about 0.2 to about 50.0 grams per liter of solution of sodium selenocyanide.

12. A photographic developer for producing direct positive images comprising an alkaline solution of l-phenyl- 3-pyrazolidone and from about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide.

13. A photographic developer for producing direct positive images comprising an alkaline solution of l-phenyl- 3-pyrazolidone and from about 0.2 to about 50.0 grams per liter of solution of potassium selenocyanide.

14. A photographic developer for producing direct positive images comprising an alkaline solution of l-phenyl- 3-pyrazolidone and from about 0.2 to about 50.0 grams per liter of solution of sodium selenocyanide.

15. A photographic developing solution having the following composition:

Water to make 1 liter.

16. A photographic developing solution having the following composition:

Grams 1-phenyl-3-pyrazolidone 10.0 Sodium isoascorbate 40.0 Sodium selenocyanid 20.0 Sodium hydroxide 30.0

Water to make 1 liter.

17. A photographic developing solution having the following composition:

Grams 1-phenyl-3-pyrazolidone 10.0 Sodium isoascorbate 40.0 Potassium selenocyanide 400 Sodium hydroxide 30.0

Water to make 1 liter.

18. A photographic developing solution having the following composition:

1-phenyl-3-pyrazolidone grams 10.0 Sodium isoascorbate do 40.0 Potassium selenocyanide do 40.0 Sodium hydroxide do 30.0 Monothioglycerol ccs 4.0

Water to make 1 liter.

19. A photographic developing solution having the fol lowing composition:

l-pheny1-3-pyrazolidone grams 10.0 Sodium isoascorbate do 40.0 Sodium hydroxide do 300 Potassium selenocyanide do 40.0 pfi dithiasuberic acid do.... 40.0 Monothioglycerol ml 5.0

Water to make 1.0 liter.

veloping agent for reducing exposed silver halide to metallic silver, and from about 0.2 to about 50.0 grams per liter of solution of an alkali metal selenocyanide, and difiusing unexposed silver halide from said exposed photographic silver halide emulsion into said receiving layer.

References Cited in the file of this patent UNITED STATES PATENTS 1,623,499 Sheppard Apr. 5, 1927 2,698,245 Land V Dec. 28, 1954 2,740,717 Yutzy Apr. 3, 1956 OTHER REFERENCES Chemical Abstracts, 34, 2281. Chemical Abstracts, 31, 5717. 

20. A METHOD OF PRODUCING DIRECT POSITIVE IMAGES COMPRISING DEVELOPING AN EXPOSED PHOTOGRAPHIC SILVER HALIDE EMULSION IN CONTACT WITH A RECEIVING LAYER CONTAINING SILVER PRECIPITATING MATERIAL FOR UNEXPOSED SILVER HALIDE, SAID DEVELOPMENT BEING CARRIED OUT IN THE PRESENCE OF AN ALKALINE SOLUTION COMPRISING AN ORGANIC SILVER HALIDE DEVELOPING AGENT FOR REDUCING EXPOSED SILVER HALIDE TO METALLIC SILVER, AND FROM ABOUT 0.2 TO ABOUT 50.0 GRAMS PER LITER OF SOLUTION OF AN ALKALI METAL SELENOCYANIDE, AND DIFFUSING UNEXPOSED SILVER HALIDE FROM SAID EXPOSED PHOTOGRAPHIC SILVER HALIDE EMULSION INTO SAID RECEIVING LAYER. 